The present state of the art relative to infusing intravenous intermittent medications involves two methods, both of which share equally in the proportion of use in today's hospital practice.
The first method utilizes an in-line burette where a special intravenous (IV) set with a calibrated chamber in the IV fluid pathway in used for receiving a premeasured dose of a drug. The drug is injected into the calibrated chamber by means of a rubber sealed opening. Generally the primary IV solution is used to dilute the drug to a volume of 50 ml to 100 ml. The primary IV solution is then manually shutoff by a stopcock placed in the fluid pathway between the primary solution container and the calibrated chamber. The drug, diluted or not, enters the patient's body until the calibrated chamber is depleted at which time, the nurse must manually restart the primary IV solution. Failure of the nurse to restart the primary IV solution within a short period after the contents of the calibrated chamber are evacuated greatly enhances the opportunity for clotting within the patient's blood vessel about the tip of the intravenous cathetes.
The second method, the so called piggyback system, utilizes the drug in a small volume "mini-container" placed at a higher level than the primary solution container. Here tubing from the mini-container joins with the tubing from the primary solution container between the primary solution container and the patient. The tubing between the primary solution container and the junction with the tubing from the mini-container incorporates a check valve which permits flow of the primary solution only when it has the higher pressure head. Thus, fluid from the mini-container will take precedence. The primary solution resumes automatically after the depletion of the fluid in the mini-container.
Disadvantages of the piggyback system is that a new mini-container must be obtained for each administration of the drug, that no opportunity is permitted for primary solution dilution, and that the total amount of the drug is not administered as there remains in the tubing that amount of the drug which is below the level in the primary solution container. In addition, the piggyback system is inheritantly an expensive system.
Thus, it is apparent that there is a need for a device for intermittently infusing drugs into a patient's body, with or without primary solution dilution, in an IV arrangement or with a secondary solution with a sequential continuous intravenous flow.